


20

by PineTrain



Series: Untitled Stories [20]
Category: Gravity Falls
Genre: Anal, F/M, Strap-Ons
Language: English
Status: Completed
Published: 2018-03-11
Updated: 2018-03-11
Packaged: 2019-03-29 17:16:12
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 706
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13931640
Author URL: https://archiveofourown.org/users/PineTrain/pseuds/PineTrain





	20

**Anonymous**  asked:

You don't have to be submissive to like anal stuff ya know.

**[twistedvirgorivaliant](https://twistedvirgorivaliant.tumblr.com/post/163670439588/you-dont-have-to-be-submissive-to-like-anal-stuff)**  answered:

> .> true

 

but then what is the trainer for?

 [pinecesttrain](https://pinecesttrain.tumblr.com/post/163676348889/you-dont-have-to-be-submissive-to-like-anal-stuff)

Dipper leaned idly against the wooden table. It’s edge poked into his firm, naked butt, and though a towel mitigated some of annoying pressure from the lacquered surface, he still found himself adjusting his posture periodically as the minutes ticked by. Mabel sure was taking her time getting ready.

There was a tension in the room’s atmosphere, a byproduct of the new line they would cross in their relationship today. While it would not be the first time something had been in his butt, and indeed Mabel herself had used a number of ever larger toys on him, there was something different about her hips rather than her hands doing the inserting. A reversal of the normal way of things in nature that made he deep instincts of the reptilian part of his brain twinge uncertainly.

He ignored them, of course. Instincts had their uses, but fear of his sister giving it to him up the bum was hardly one of them, especially when he was the one to suggest the idea. He was excited, in fact, and he fed off the tension, enjiying he tingle of adrenaline beginning to flow through him.  
  
*thud*

*thud*

*thud*

Dipper quirked his eyebrow at the sound of approaching footsteps. Was Mabel being dramatic? They sounded too heavy and awkward for his light and elegant sister.

*thud*

*thud*

*thud*

He turned his head slightly, eyeing the door suspiciously as the footsteps halted just on the other side. The moments trickled past as nothing happened. Then tension was suddenly different. There was an imposing weight to the air around the door, almost as though ripples of energy flowed from it. Almost as if he were feeling a rise of nervousness, perhaps even fear, at what lay behind it.

Nonsense. Dipper took a breath and steeled himself. He would not let these foolish instincts take control.

*WHAM*

Dipper didn’t flinch at all when Mabel kicked the door open, but his eyes did pop at what she held. It had thrown her off-balance when she kicked the door and she teetered backwards for a few seconds as the massive object reached above her shoulder. Perhaps a meter long, it reminded him of an anti-materiel rifle, though one usually braces those against their shoulder and not their crotch.

Catching her balance, Mabel slowly fell forward, releasing the enormous purple dildo from her supportive hug against her body. Her foot hit the floor loudly, the silicone member slapping into her hands immediately after. Her knees buckled slightly from the force, but she stayed standing.

Mesmerized by the thing’s length and girth, Dipper took a fully minute to tear his eyes away and meet Mabel’s. The glimmer of mischievous excitement in them was blinding. His own soon watering from the forceful energy they exuded he caught a last glimpse of her eyebrows waggling harder than he’d ever seen before.

Closing his eyes in relief, memories played across the back of the lids. He hadn’t thought it odd at the time, but the fact that the toys she used in the past had grown and grown was now front and center as he understood Mabel’s plan. She had been training him for this day. Since the very first time he mentioned it. Or no, since before. There were simply too many toys for her to have started this plan right then. She had to have been collecting since before.

“Ready, Dipper?” she asked.

He reopened his eyes. Still at the doorway, she had hunched over to support the dildo like an awkwardly placed spear. If he was going to turn back, now was the time.

But Dipper wasn’t that sort of person. With a nod, he turned around and assumed the position against the table. He glanced back to see Mabel shifted her weight in preparation to move in. He thought back to his unwitting training and calmed himself, grabbing hold of the tension washing through him and turning it back into the earlier excitement.

“HERE COMES BIG MOMMA!” Mabel screamed as she began her charge.

Their lives changed forever that day.


End file.
